It was definitely inspired casting to put Downey in the role. His life has quite a few similarities to Tony Stark's actually. I think since the casting of Tobey Maguire in Spiderman, hollywood realized they could start casting smaller actors with more acting chops instead of just guys that look the part physically. Bale is also owning the part of Batman like nobody has before. I thought Bana was fine as Banner but Norton is an interesting choice. I'm looking forward to who they'll choose for the Flash, Captain America, and Thor. Looking forward to this film for sure.